Because it was snowing hard, buses could _________ get through, _____did taxi appear on the street.

A．both; and

B．either; or

C．not only; but also

D．neither; nor

急性心肌梗死与不稳定心绞痛的主要鉴别是（）

A.疼痛的部位不同

B.疼痛的性质不同

C.疼痛的诱因不同

D.是否有心电图改变

E.是否有心脏生物学标志物的改变