The way  小题1: people spend their holidays has changed a lot.  小题2: seems that people are changing their  小题3: (mind) and they want to explore the outside world. The seaside still has  小题4:different attractions for people. But it will be possible to decrease(下降) because  小题5: the pollution. Now people  小题6: (persuade) to travel abroad which can widen their knowledge about the world. Another track is that camping is  小题7: (rise). People insist  小题8: getting close to nature. Anyway, people should refer to journals, guide books and even ask advice  小题9: the experienced  小题10: they begin their travel.

心房扑动的特征是（）.

A.心室率通常为100～160次／分

B.心室率规则

C.QRS波群形态正常

D.扑动波之间等电位线消失

E.P波消失代之以规律的锯齿状扑动波