血吸虫病的传播途径为()。
A.呼吸道
B.消化道为主
C.呼吸道和消化道
D.皮肤粘膜接触
E.蚊子媒介
参考答案:D
A.Because she could not sleep well at night.
B.Because she hoped to earn more money.
C.Because she could not find a daytime job.
D.Because she needed a change and a lighter job.
20CrMnTi的含碳量是0.2%。()