血中Hb含量低于多少时,即使重度缺氧,亦难发现发绀()
A.<50g/L
B.<60g/L
C.<70g/L
D.<80g/L
E.<90g/L
参考答案:B
Do you think shopping online will ______ take the place of shopping in stores?
A.especially
B.frequently
C.merely
D.finally
胃溃疡腹痛的规律是()。
A.无明显规律性
B.疼痛-排便-加重
C.进食-疼痛-缓解
D.疼痛-进食-缓解
E.疼痛-排便-缓解