何谓车钩的三态作用？
参考答案：
车钩的三态作用是指车钩的闭锁位置、开锁位置、全开位置的作用原理。
Write _and try not to make any mistakes.[ ]
A. as careful as possible
B. as carefully as you can
C. most careful
D. more careful
食管、胃底静脉曲张破裂出血
A．鲜红血便 B．创伤后呕血 C．出血伴腹痛、发热 D．呕血及黑便 E．出血来势凶猛，以呕血为主
