He___to meet us at the station, but didn't see us.
A. did go
B.did went
C. goes
D.had
答案:A
在UNIX系统中,文件分成3类,即普通文件、【 】和特殊文件。
高产育种的策略主要有()。①优质育种②稳产育种③矮杆育种④理想株型育种⑤高光效育种
A.①+②+③
B.②+③+④
C.③+④+⑤
D.①+②+③+④+⑤
E.①+⑤