第二部分：英语知识运用
第一节：单项填空（共15小题，每小题1分，满分15分）
从A、B、C、D四个选项中，选出可以填入空白处的最佳答案。
21. You will surely get access ______ the internet; it’s only _____ matter of time.
A. of; a B. to; a C. on; the D. to; the
22. He works so hard that I never doubt ________ he will succeed.
A. whether B. how C. that D. when
23. I found Mary _______ at the desk, ________ her homework carefully.
A. sitting; do B. sit; doing C. seated; do D. seated; doing
