低钾血症时，最早表现为（）
A.肌肉无力
B.腱反射减退
C.肠麻痹
D.心电图出现"U"波
E.恶心、呕吐
参考答案：A
— What are your hobbies?
— I enjoy ____ coins and stamps. [ ]
A. collect
B. collecting
C. to collect
D. collected
Is this elephant _____ China or _____ India?[ ]
A. from, to
B. from, from
C. to, to
D. at, in
