用马铃薯的块茎来种植时,最关键的是马铃薯块的大小.(判断对错)
If we spend too much time on the Internet, we won't have enough time to study. , working on computers too long may cause headaches or sore eyes.
读撒哈拉以南非洲示意图,完成下面小题。
方程组x+y=1x2-y2=9的解集是( )