任何一个自然数（ 0除外 ）的因数至少有两个．______．
自然数1的因数只有1个．所以题干说法错误．
故答案为：×．
—I ______ for you for two hours, but in vain. Where did you go?
—I ______ at my uncle’s.
A．had looked; may have stayed
B．looked; must have stayed
C．have looked; may be staying
D．looked; must be staying
盘点有哪几种类型？
