活性污泥在培养驯化时,为了防止池内出现厌氧发酵应该怎么做?
参考答案:
停止曝气到重新曝气的时间不应超过2小时。
完成句子 根据中文意思,用单词或短语的适当形式填空,完成句子。(5分)
小题1:你家离莆田车站有多远?
__________ is it from your home to Putian Railway Station?
小题2:为了与她保持联系,我记下了她的电子邮件地址。
I wrote down her __________ address in orderr to keep in touch with her.
小题3:《功夫熊猫2》如此精彩以至于许多孩子都喜欢看。
The movie Kung fu Panda 2 is __________ wonderful __________ many children enjoy watching it.
小题4:如今越来越多的人关注食品安全。
Nowadays __________ people pay attention to food safety.
小题5:在日本当你去拜访朋友时,进门之前要脱掉鞋子。
When you visit a friend in Japan, you should __________ your shoes before entering his home.
如图是用来粉刷墙壁的涂料滚的示意图,使用时用撑杆推着涂料滚沿墙壁上下滚动,把涂料均匀地粉刷到墙壁上。撑杆的重量和墙壁的摩擦均不计且撑杆足够长,粉刷工人站在离墙某一距离处缓缓上推涂料滚,使撑杆与墙壁间的夹角越来越小,该过程中撑杆对涂料滚的推力为F1,涂料滚对墙壁的压力为F2,下列说法正确的是
A.F1增大,F2减小
B.F1减小,F2增大
C.F1、F2均增大
D.F1、F2均减小