导管结石好发于()
A.腮腺
B.颌下腺
C.舌下腺
D.黏液腺
E.浆液腺
参考答案:B
It took Li Ming an hour _____ his bike yesterday. [ ]
A. to repair
B. repairing
C. repaired
D. repair
高煤比对焦炭质量要求是()。
A.更好的原始强度和更好的原始粒度
B.更好的高温强度
C.降低焦炭灰分