The phrase "held back” in paragraph 1 means________

Orchids are unique in having the most highly developed of all blossoms, in which the usual male and female reproductive organs are fused in a single structure called the column. The column is designed so that a single pollination will fertilize hundreds of thousands, and in some cases millions, of seeds, so microscopic and light they are easily carried by the breeze. Surrounding the column are three sepals and three petals, sometimes easily recognizable as such, often distorted into gorgeous, weird, but always functional shapes. The most noticeable of the petals is called the labellum, or lip. It is often dramatically marked as an unmistakable landing strip to attract the specific insect the orchid has chosen as its pollinator. To lure their pollinators from afar, orchids use appropriately intriguing shapes, colors, and scents. At least 50 different aromatic compounds have been analyzed in the orchid family, each blended to attract one, or at most a few, species of insects or birds. Some orchids even change their scents to interest different insects at different times. Once the right insect has been attracted, some orchids present all sorts of one-way obstacle courses to make sure it does not leave until pollen has been accurately placed or removed. By such ingenious adaptations to specific pollinators, orchids have avoided the hazards of rampant crossbreeding in the wild, assuring the survival of species as discrete identities. At the same time they have made themselves irresistible to collectors.

The word "their" in line 12 refers to .......

The advent of the Internet may be one of the most important technological developments in recent years . Never before have so many people had access to so many different sources of information . For all of the Internet's advantages , however , people are currently becoming aware of some of its drawbacks and are looking for creative solutions . Among the current problems , which include a general lack of reliability and numerous security concerns , the most crucial is speed .

First of all , the Internet has grown very quickly . In 1990 , only a few academics had ever heard of the Internet . In 1996 , over 50 million people used it . Every year , the number of people with access to the Internet doubles . The rapid growth has been a problem . The computer systems which run the Internet have not been able to keep up with the demand . Also , sometimes , a request for information must pass through many routing computers before the information can be obtained . A request for information made in Paris might have to go through computers in New York , Los Angeles and Tokyo in order to obtain the required information . Consequently , the service is often slow and unpredictable. Service also tends to be worse when the Internet is busiest - during the business day of the Western Hemisphere - which is also when companies need its service the most.

What is true of Lake Vostok? 

The word “lies” in the first paragraph could be best be replaced by ______.

The word “fledgling” in the third paragraph could be best replaced by which of the following?

The word “harness" in paragraph 4 is closest in meaning to .........

Technology has utterly transformed our ability to communicate with each other. Linking to each other both literally and figuratively, many of us connect through cell phones, email, instant messaging, blogs, and networking web sites, yet we may be less connected to each other than we think. According to a study, Americans are becoming increasingly socially isolated. The study reveals, for example, that one quarter of Americans say that they have no one to discuss important personal issues with, and that the number of close friends that American have has dropped from three to two. Meanwhile, the Boston Globe reports that this spreading isolation is experienced more sharply among those with less education, people of color, and older Americans. Unsurprisingly, those who are young, white, and well educated tend to have stronger social networks. From my own experience I have to say that I’ve never felt more connected, thanks to a web of friends, family, and colleagues. One of my closest friends is someone I met through an online discussion group who lives hundreds of miles away from me. We have met faceto-face only twice, yet our regular electronic correspondence and cell phone calls sustain our close friendship. And, speaking of blogging, my blog has introduced me to people I would never have met otherwise and has led to enduring and important friendships. On the other hand, I recently saw a scene unfold that proved to me how deeply disconnected we as Americans have become. I had just wrapped up a presentation on mediation at a family therapy center. As I was leaving, I noticed a mother and her teenage son who had just completed their session with their family therapist. After making their next appointment, they both took out their cell phones, placed calls, and began loud conversations with whoever was on the other end. I walked out behind them to the parking lot to my car. They both jumped into their SUV, and, as I saw them drive off, they were still talking on their cell phones. But, alas, not to each other. 

Which of the following has nothing to do with the isolation among Americans?