建设工程担保中，担保金额在担保有效期内逐步减少的担保是( )。
A．投标担保
B．支付担保
C．预付款担保
D．履约担保
参考答案：C
根据首字母和汉语提示完成单词。
1. The woman has studied English s______1990.?
2. —Have you heard a______ Lei Feng?
—Yes, of course.?
3.The plane has a______ in Tianjin already?
4. In fact, since 1989 ______ (工程)Hope has built schools all over China.?
5. How long has Lingling ______ (认识)Sally?
下列属于人体必需的微量元素的元素是
A．铁、碘、氟、锌、锰
B．铜、钙、硒、铁、铬
C．碘、铜、汞、锌、铬
D．硅、铅、钒、锌、碘
E．氟、硒、铅、铁、碘
