We have a laptop at home,  but I ______ it. [ ]

A. often use

B. don't often use

C. doesn't use

D. often don't use

患者因外伤来医院，查体：神志尚清楚，诉口渴，皮肤苍白，稍冷，脉搏110次/分，收缩压90～70mmHg，脉压小，尿少，浅静脉塌陷。试估计此时患者的失血量约占全身血容量的（）

A.<20%

B.20%

C.20%～40%

D.>40%

E.50%