二．单项填空。（共15小题，每小题1分，满分15分）
21. It is _____that he has been addicted to the drugs and has difficulty quitting it.
A. obviously B. apparently C. possibly D. likely
22. The police looked into the case carefully and found the thief had entered the house ______ a ladder.
A. by the means B. by all means C. by ways of D. by means of
23. Many students listened to the lecture, but I wondered how much they ______.
A. took out B. took up C. took off D. took in
