Many people and organizations have been making every possible effort in order to save ________ species.

A. Global warming and its advantages.

B. Global warming and its negative effects.

A. Not until we had reached the top did we realize how far we had come.

B. Having realized how far we had come, we reached the top.

C. Only after we realized how far we had come had we reached the top.

A. She needn't meet her children until the operation has finished.

B. She may not meet her children until the operation has finished.

C. She shouldn't meet her children until the operation has finished.

A. Young people's disinterest in their grandparents' stories

B. Young people's tendency to neglect their grandparents

C. Grandparents' loneliness in their old age

A. Lena said that she had invited me to her birthday party the following day.

B. Lena said that she would invite me to her birthday party tomorrow.

C. Lena said that she would invite me to her birthday party the following day.

A. He regretted writing his letter of application earlier

B. He wishes he had written his letter of application earlier

C. He wishes he hadn't written letter of application earlier

A. waste