预防麻疹最关键的措施是:().
A.严格隔离病人
D.易感者注射丙种球蛋白
C.接种麻疹减毒疫苗
D.病室开窗通风
E.流行期间易感儿不到公共场所
参考答案:C
Choose the right word to complete the sentence. 选出正确的单词完成句子。
1. —May I use (your / yours) bicycle?
—I'm sorry. (My / Mine) is not here.
2. Look! The cat is washing (it's / its) face.
3. The supermarket is (to / too) (noisy / noise). I don't like it.
4. John (and / with) Mary were (in / at) home yesterday.
5. There are (third / three) girls in the room. The first girl is my sister.
They are (quite / quiet) happy.
冲洗照片时,需将底片浸泡在大苏打(Na2S2O3)溶液中,使影像固定下来,这一过程叫“定影”.大苏打中硫元素的化合价为( )
A.0
B.+2
C.+4
D.+6