【单选题】He has some trouble ____ his classmates but he has no trouble ____ doing his lessons. [ ]
【单选题】―What your English teacher doing now? ―He _____ a newspaper.
【单选题】叶酸缺乏可使胎儿神经管畸形的发病率增高,因此建议妊娠前和妊娠早期每日补充叶酸为多少维克
【简答题】发动机的磨合规范由( )( )和( )组成。
【单选题】He has some trouble ______ his classmates, but he has no trouble ______ doing his lessons.
【单选题】—What were you doing when she dropped in? —I for a while and_________ some reading.
A.
was playing; was going to do
C.
had played; was going to do