硬质合金钢分为()、钨钴钛类、通用硬质合金。
参考答案:钨钴类
I coutdn't have got to the meeting on time____________ an earlier train.
A.if I had not caught
B.unless I had caugh
C.if ! did not catch
D.unless I caugh
消渴病怎样辨证治疗