腭扁桃体发育达高峰的年龄是（）
A.6个月内
B.1岁末
C.2～3岁
D.3～4岁
E.4～10岁
参考答案：E
His parents often encourage him __ hard.[ ]
A. work
B. working
C. to work
D. works
Visual Basic逻辑运算符Xor、Or、Eqv、And中，级别最高的运算符是 ______。
A．And
B．Or
C．Eqv
D．Xor
