Most of the time, he has no trouble ______________ the people from different countries.
A:understand
B:to understand
C:understanding
下列各句中,划线的成语使用不恰当的一项是( )
如图所示,数轴上有A、B、C、D四个点,分别对应的数为a、b、c、d,且满足a=﹣2,|b|=0,(c﹣12)2与|d﹣18|互为相反数.
eye的复数形式是 ____ .