I can still remember that it is since the 1990’s, _____ we began to use cell phones,_______ the number of mobile users has greatly increased．

A．while; when

B．when; what

C．before; that

D．when; that

属于心虚胆怯型心悸的主症是

A．胀满疼痛，攻窜不定
B．胀满疼痛，腹痛拒按
C．腹部刺痛，固定不移
D．腹部胀痛，嗳腐吞酸
E．腹痛喜按，得温则减