题目

用容量瓶配制一定物质的量浓度的Na2CO3溶液时，下列各项中，可能导致其实际浓度偏低的是( )A. 在用天平称量时，托盘里的部分Na2CO3吸收了水分，形成了少量结晶水合物B. Na2CO3溶解时放出热量，未冷却立即配制溶液C. 用蒸馏水洗涤溶解过Na2CO3固体的烧杯，并将洗涤后的溶液注入容量瓶D. 定容时俯视瓶颈刻度线 完形填空。      We got    1    3,000 letters and emails from our    2    about their New Year's Resolutions. Many girls said they are going to exercise more    3    . Some parents said they are going to study the subject their kidslearn at school. They want to communicate with their children. An old    4    said he is going to find a job as an    5    teacher. A boy    6    Tom Smith said he is going to start    7    a new language this year. Andan old lady said," I    8    my resolution a short time ago, I am going to    9    my grandson carefully andto   10    a loving grandmother." (     )1. A. more     (     )2. A. readers  (     )3. A. keep fit(     )4. A. lady     (     )5. A. math   (     )6. A.called    (     )7. A. study    (     )8. A. make    (     )9. A. look after(     )10. A. do      B. over           B. read            B. to keep healthy B. women         B. usual         B. calls          B. studied        B. maked           B. look  for       B. be           C. to        C. reading    C. to be fit C. man       C. English  C. calling   C.studying    C. made     C. look to   C. as