根据短文,判断正误。
Look at this desk. It's Jim's desk. It's brown. Jim's book is on it. It's an English book. His pencil-box is on it, too. His pencil is in his pencil-box. But where's his pen? He can't find it.
在一个暗箱里放有a个除颜色外其他完全相同的球,这a个球中红球有4个,每次将球搅拌均匀后,任意摸出一个球记下颜色再放回暗箱,通过大量重复摸球实验后发现,摸到红球的频率稳定在0.25,那么可以推算出a大约是( )
—They are horses.
下列运算正确的是( )