ActionForm中的validate方法返回什么值，表明是验证成功（）A.nul

用托盘天平称量固体药品时，左盘砝码为5g，游码为0.3g，指针向右偏转，药品的质量一定是（　　）

A．等于4.7g

B．大于4.7g

C．小于4.7g

D．大于5.3g

债权人领取提存物的权利自提存之日起( )年内不行使而消灭。

A．1

B．3

C．5

D．10

长期大量应用头孢菌素类抗菌药物的患者，需注意适当补充（）。

A.维生素A和维生素D

B.维生素B和维生素K

C.维生素C和烟酸

D.维生素E和叶酸

E.维生素B12和叶酸

如图，电磁铁通电时，小磁针静止在图示的位置上，小磁针的a端是______极；当滑动变阻器的滑片向右移动时，电磁铁的磁性将______．

Following a year of fast development, by the first quarter of this year, China has had about 1,100 e-commerce websites .

A．China had about 1,100 e-commerce websites by the end of last March

B．by the end of the first quarter of this year, China has had about 1,100 e-commerce websites

C．by the end of this recent past March, China has about 1,100 e-commerce websites

D．by the end of this first quarter, China had about 1,100 or so e-commerce websites