1. The children have not yet learned to punctuate correctly.
    这些小学生尚未学会正确使用标点符号.

2. He answered quite correctly.
    他答得很对。

3. How hard I have been trying to get every sound right, to spell every word correctly and to speak the little English I know!
    为了发好每个音，拼对每个单词，说出我知道的那点英语，我付出的努力太大了！

4. Children do not learn sounds correctly at once, but make countless mistakes.
    儿童不是立即就能学会正确发音的，而是会犯无数的错误。