21. The pictures show many small, round tumors(肿瘤) inside the patient, which are ___of a kind of cancer.
A. signs B. signals C. Symbols D. marks
22. There wasn't enough water to___ the ship, so the sailors had to ask for help.
A. support B. hold C. Raise D. float
23. Having these types of coffee regularly will increase chances of your becoming overweight, and___ increases your risks of developing some diseases.
A. in general B. in return C. in total D. in turn
