These tablets are harmful to the children，so they _________ out of their reach．

A.should keep

B.should be kept

C.would keep

D.will keep

答案及解析： B

解析：

代词they指these tablets，该句主语是谓语动词动作的承受者应用被动语态.这句意为“这些药片对孩子们有害，所以要放在他们够不到的地方”.答案为B.