消化性溃疡的特点是
A.持续反复发作
B.慢性过程呈反复发作,病史可达几年甚至十几年
C.发作周期性,与缓解期相互交替
D.发作时上腹痛呈节律性
E.发作时上腹钝痛
参考答案:B,C,D
The man _____ his coat when he walked into the warm room.
A.took away
B.took off
C.took down
D.took out
导火索的用途是产生并传递火焰,引爆炸药。