同一地区起源的蔬菜，在进化过程中所受主要自然条件的影响大致相同，它们都有相当明显的共同的生物学特性。
参考答案：对
— Bob, could you help me _____ when the earliest train will leave for Shanghai?
— OK, I'll do it right away.[ ]
A. look out
B. get out
C. find out
D. take out
Since we ________ our homework now. Let’s have a rest.
A．do
B．are doing
C．will do
D．have done
