把幼嫩的植物茎掐断,从茎的断面上会渗出汁液,汁液来自于[ ]
A.茎内木质部的筛管
B.茎内韧皮部的筛管
C.茎内木质部的导管
D.茎内韧皮部的导管
答案:C
— The shoes are very nice. I’ll take them.
— You’d better ______ first. I’m afraid the size is a bit small for you.
A.pay for them
B.take them off
C.put them on
D.try them on
我国国家标准按约束性可分为
A.强制性标准、试行标准、推荐标准B.强制性标准、推荐性标准C.强制性标准D.推荐性标准E.试行标准