Facing starvation as a result of drought, they had no ________ but to eat the roots of the trees. [ ]

A. concern 

B. command

C. shortcoming  

D. alternative

长期卧床对心血管系统的影响以下哪项是错误的

A．基础心率减慢

B．冠状动脉血流灌注减少

C．中心血容量增加

D．最大摄氧量(VO₂ma下降

E．易发生直立性低血压