It is better to teach a man how to fish than ____________ him fish.

A．to find

B．offer

C．to give

D．provide

叶粉末经微量升华得油状物，加硫酸2滴及香草醛结晶少量，初显黄色至橙黄色，再加水1滴，即变紫红色的药材是（）

A.薄荷

B.广藿香

C.穿心莲

D.荆芥

E.青蒿