常见工程包括以下几类()。
A、工程服务制工程
B、督导调试制工程
C、督导服务制工程
D、硬件合作制工程
参考答案:A, B, C
— If the traffic hadn't been so heavy, I could have been back by 6 o'clock.
— What a pity! Tina _____ here to see you.[ ]
A. is
B. was
C. would be
D. has been
在维持或消除植物的顶端优势方面,下面哪两种激素起关键性作用()。
A.IAA和ABA
B.CTK和ABA
C.IAA和CTK
D.IAA和GA