幼茎木质化后,造成根部或根茎部皮层腐烂,幼苗逐渐枯死,但不倒伏,称()。
A.种芽腐烂型
B.猝倒型
C.立枯型
D.溃疡型
参考答案:C
根据下面一篇短文的内容判断下面句子的正误,正确的用“A”表示,错误的用“B”表示。
Tom is a little boy . He is seven .Today his mother takes him to see his uncle. His uncle's home is very far from theirs. So they are going there by bus . There are only twenty people on the bus .They all sit on the seats. Tom is very happy. He is running about on the bus, so his mother says, "Don't run! Sit down,please!" " I like to see my uncle very much. I want this bus to go faster."Tom says.
小题1:Tom goes to see his uncle with his mother.
小题2:Tom's home is very far from his uncle's.
小题3:Tom and his mother go home by bus.
小题4:Tom and his mother run on the bus.
小题5:Tom's mother tells him to sit down.
关于抽样误差描述错误的是()
A.是不可避免的
B.是可控制的
C.与调查误差不同
D.抽样方法不同,产生的抽样误差也不同
E.不是抽样所特有的误差