The teacher had the students __________ all the words they didn’t know.

A．looked up

B．looking in

C．look up

D．look at

结石长期存在，可引起的尿路恶性肿瘤为

A．移行上皮癌

B．鳞状上皮癌

C．以上都不对

D．肉瘤

E．腺癌