【简答题】竖式计算(除不尽的保留两位小数) 19.19÷0.95 56.29÷6.1 23÷33 7.41÷0.57 21÷240 3.85÷0.76.
【简答题】(本题4分)按要求写出下列反应式。 (1)工业电解饱和食盐水制Cl 2 (离子反应方程式): (2)CH 3 CHO与银氨溶液发生银镜反应(化学反应 方程式):
【单选题】The main purpose of the text is to______.
A.
convince the reader that vaccines are not as safe as many think
B.
educate the reader on how vaccines are used and some of their dangers
C.
educate the reader on the circumstances that would neccesitate widespread vaccinations
D.
present the method by which vaccines are used through the case of the smallpox vaccine
【单选题】According to Paragraph 6, which of the following is true of the effect of vaccines on different groups of people?
A.
The vaccines will not be effective on unhealthy young adults
B.
The elderly will be less likely to have major complications after vaccination.
C.
The vaccines are effective on people of all ages if they are healthy.
D.
Flu vaccines are of no use for old people or people with chronic diseases
【简答题】写出下列反应式: (1) (2) (3) (4) (5)