双发双收声波所记录的时差为两个接收探头之间所产生时差()。
A、绝对值
B、平均值
C、上限值
参考答案:B
阅读下面短文,根据上下文填入适当的词语,或使用括号中的词语的适当形式填空。
On keeping a Diary in English
Keeping a diary in English is one of the 小题1:___ __ (effect) ways to improve our English writing ability.
小题2:______ (compare) with other forms of writing, it is shorter and takes 小题3:______ time. It can help us to develop the habit of thinking in English. 小题4:______ we persist in this practice, gradually we’ll learn how to express ourselves in English. In keeping a diary in English, we certainly run up against many 小题5:____ __(difficult). In the first place, 小题6:______ often happens that we have trouble 小题7:_________(find) appropriate words and phrases to give expression to our mind. Secondly, there are many idiomatic ways of saying things in Chinese. And it is extremely hard for us to put them into English properly.
As far as I 小题8:____ __ (concern), my suggestion is that we should always have a notebook and a Chinese-English dictionary within easy reach. Whenever something beats us, we can first put it down in our notebook and then consult our dictionary. We can also turn to our English teacher for help, if necessary. In short, I believe that it is 小题9:______ great use to keep a diary in English for 小题10:______ development of our writing skills.
流感病毒易于变异的物质基础是()
A.病毒毒力强
B.无包膜病毒
C.临床表现多样化
D.分节段的基因组结构
E.A+B+C