请教一道改错题，谢谢！ 请教, 改错

lnddshw

Task 4
After Asian elephants have been captured, they are
Easily（
training错.） They seem to become contended and
（ever错） happy when well treated. An Asian elephant quickly
learns to know its master and
（understand错） by the tone of
（their错）
voice whether the man is pleased or angry. Because
of their strength and brightness, （so错） these elephants are
valuable work animals in India.

DZ

training--trained
ever--even
understand--understands
their--his
so 去掉
my opinion

lnddshw

多谢！