1. [单选题]树皮中的外树皮全是死组织，内树皮主要是活组织。( )
A. 正确
B. 错误
2. [单选题]----I have tried very hard to find a solution to the problem, but in vain ----why not consult with Frank? You see, _________.
A. great minds think alike
B. two heads are better than one
C. a bird in the hand is worth two in the bush
D. it’s better to think twice before doing something
