Choose the underlined part that needs correcting

It was in 1971 that  transatlantic supersonic transportation became commercially availability

It _______ half of your plate should consist of vegetables and fruits.

The doctor told him not to talk during the meditation.

Smartphones, laptops and tablets are the modern devices __ have changed the way we learn.

Some modern couples organize their marriage and work out the tasks and duties, which may gradually turn their marriage into a business or ______ relationship.

Don't put off doing your homework until tomorrow. Do it right now, _____?

Unable to remember _____, he walked around the neighborhood looking for his car.

Choose the word /phrase that is CLOSEST in meaning to the underlined part in each sentence below

The USA is one of the most culturally diverse countries in the world.