—What are you doing?
—I am _________ a letter.[ ]
A. write
B. writing
C. writes
答案:B
He up the medicine with water. [ ]
A. ate
B. had
C. swallowed
D. swept
国际收支系统记录的是一定时期内一国居民与非居民之间的()。
A.贸易收支
B.外汇收支
C.国际交易
D.经济交易