由题意可知：从词法上讲heIpfuI，和hard-working都是形容词。从词意上讲：hard-working是勤奋的，卖力的，它在句子中往往作定语，后面跟名词。

My mother is a hard-working and well spoken woman.

句中hard-workin9作定语，修饰woman

helpful是有帮助的，有力的，它在句子由往往作表语。

To read a lot is helpful to the students.

句中helpful作表语