某男，30岁，3个月来经常出现头痛、眩晕、失眠、面色苍白、平静状态有气短甚至端坐呼吸，自觉心悸，心率加快，食欲减低，腹胀等症状。

对该患者的治疗应采用（）

A.对因治疗

B.对症治疗

C.对因治疗并对症治疗

D.先对因治疗

E.先对症治疗

What _____ the forest of the USA in the last 350 years?[ ]

A. has happened to

B. is happened to

C. has happened at

D. is happening