乳牙患龋高峰年龄段为
A.2~3岁
B.3~4岁
C.5~6岁
D.7~8岁
E.9~10岁
参考答案:D
治疗并殖吸虫病的首选药物是()
A.喹诺酮
B.别丁
C.三氯苯达唑
D.氯喹
E.吡喹酮
I did not watch TV last night ______ I had a lot of homework to do. [ ]
A. if
B. because
C. when
D. but