设向量组（Ⅰ)的秩为r，又向量组β1，β2，…，βr为（Ⅰ)中的线性无关组.证明：β1，β2，…，βr可作为（工)的极大无关组.

Why do children tend to be violent if they have been spanked often？

A．Because spanking brings only fear, which is the origin of violence.

B．Because spanking fails to build a mutual understanding between parents and children.

C．Because their parents have set them a model of violence being accepted.

D．Because children may take it for granted that violence is a way out for problems.

She ______ soon after dark and arrived home an hour later.

A、had set out

B、set out

C、have set out

D、had been set out

The writer suggests that it is a good idea to set aside some money because______

A．you will not be able to carry out your budget

B．people usually spend more than they plan to do

C．every family may have emergency

D．others may want to borrow some money from you

______ refers to the phenomenon that the same word may have a set of different meanings.

A．Homonymy

B．Antonymy

C．Polysemy

D．Homophony

______refers to the phenomenon that the same word may have a set of different meanings.

A．homonymy

B．antonymy

C．polysemy

D．homophony

A．The stimuli set them off... build collectively

B．The stimuli that set them off... building collectively

C．The stimuli setting them off... they build collectively

D．Being set off by stimuli... their building collectively

In order to set the system, you should have all passengers get out of the vehicle.

A．Y

B．N

C．NG

The writer suggests that it is a good idea to set aside some money because______

A．you will not be able to carry out your budget

B．people usually spend more than they plan to do

C．every family may have emergency

D．others may want to borrow some money from you