-ics
（指以-ics结尾的名词，如acoustics，dynamics，ethics，mathematics和politics。）
就语源讲，以-ics结尾的名词属于复数形式，但习惯上不一定被看作复数。虽然意见并不一致，但大概遵守着下面几条规则：
（1）科学名称被看作单数。例如：Mathematics deals with space and number. 和Politics is now taught in all schools.
（2）科学名称前面加了my、the、such等词被看作复数。例如：My mathematics are weak. Their politics are now on a high level. 和Such ethics are of little value.
（3）行为等的名称被看作复数。例如：Aerobatics take a lot of learning. 和Heroics are out of place here.
（4）如果后面有属于单数形式的表语，便看作单数。例如：Mathematics is your strong point. 和Dramatics is his hobby.
