I can't write on. I have _____ ink(墨水). [ ]
A. run out of
B. run out
C. ran out of
答案:A
微生物的哪些特征使其能称为环境污染净
铜管在加工制作时,其切断方法为()
A、锯断
B、割刀割断
C、气割
D、錾断