两个质数的和是20.它们的积是91.这两个质数分别是______和______.
因为91=7×13,
又符合7+13=20,
所以这两个质数分别是7、13.
故答案为:7,13.
I don't think it is cold today, ? [ ]
A. do I
B. don't I
C. is it
D. isn't it
具有燥湿化痰、祛风解痉、散结消肿功效的药物是()
A.天南星
B.蝉蜕
C.海藻
D.防风
E.蕲蛇