Ⅱ单项选择（共15小题；每小题1分，满分15分）
1. I ________ to my cousin’s birthday party last night, but I ________ busy with piles of work.
A. went, had been B. had gone, was
C. would go, had been D. would have gone, was
2. The underground system ________ in the city now will be opened next year.
A. constructing B. to be constructed
C. is constructing D. being constructed
3. I’m wondering ________ Mr. Gross realized the task was extremely difficult to complete.
A. when it was that B. when was it that
C. it was when that D. was it when that
4. Not until ________ real hardship ________ the love we have for our families is important.
A. he went through, has he realized B. did he go through, he realized
C. he went through, did he realize D. did he go through, he had realized
