下列变化属于化学变化的是 [ ] A.瓷碗破碎 　 B.牛奶变酸 　 C.轮胎

以“Animals, our friends!”为题写一篇短文。

要求：1）70词左右，开头已给出，不计入总词数。

2）展开自己的想象，可以通过“dogs, cows, hens 等几种动物来进行说明。

3）适当运用get on well with….; get …from…; guide dogs; the blind; milk; hens; eggs; interesting; for example; save 等词汇。

4）意思连贯，语句通顺，书写工整。

Animals, our friends!

It is important to ________________________________________________________________

_____________________________________________________________________________________

_____________________________________________________________________________________

_____________________________________________________________________________________

1是任何自然数的因数．______．（判断对错）

Password is a secret series of (69) that enables a user to access a file, computer, or program. On multi-user systems, each user must enter his or her password before the computer will respond to (70) . The password helps ensure that (71) users do not access the computer. In addition, data files and programs may require a password.

A．power

B．authorized

C．accredit

D．unauthorized

利用超滤技术和反渗透技术相结合，可以实现电泳槽液和后冲洗系统全封闭循环。( )

在工作中连续发生熔断丝被烧断，应查明原因，切不可擅自（）或用（）代替。