Dogs _____ wear clothes. [ ]
A. isn't
B. aren't
C. don't
D. doesn't
答案：C
佝偻病发病机制中下述哪项不正确
A．甲状旁腺功能代偿性亢进
B．骨钙释出
C．肾小管对磷的重吸收增加
D．局部骨样组织堆积
E．碱性磷酸酶分泌增加
Ann helps Lily with her homework ______ eight o’clock ______ Sunday. [ ]
A. on; in
B. in; on
C. at; on
D. at; in
