Whenever you enter the reading room, you can find all the students _____ at their desks, with their attention

_____ on the books, except Tom. [ ]

A. sitting, fixing

B. to sit, fixed

C. seating, fixing

D. seated, fixed

对硝酸甘油作用叙述不正确的是

A．扩张脑血管
B．扩张冠脉血管
C．心率减慢
D．降低外周血管阻力
E．扩张静脉