河姆渡居民和半坡居民过定居生活的决定因素是[ ]
A.建造房屋
B.原始农业出现
C.使用磨制石器
D.原始手工业出现
答案:B
— What a pity!
— Yes, I ____ his not trying it, but in vain. [ ]
A. was suggesting
B. will suggest
C. would suggest
D. had suggested
可用1:15000高锰酸钾洗胃的是()。
A.氰化物中毒
B.敌敌畏中毒
C.乐果中毒
D.安眠药中毒
E.敌百虫中毒