血吸虫病肠道病变主要是
A．病变累及直肠、乙状结肠、降结肠
B．肠黏膜形成溃疡
C．严重者发生肠狭窄
D．病变主要累及升结肠
E．前三项都对
参考答案：E
It is always difficult being in a foreign country, __________if you don’t speak the language.
A．extremely
B．naturally
C．basically
D．especially
国家规定的外排气含尘浓度指标是150mg/m3
