一个好的句子中，每个等立成分都要以相同的形式出现。这种句法加强了文字的功力，使文章产生更大的效益。
如果同一句中应该等立的成分不对应，不但效益不好，而且也是一种句法上的缺陷。
下面两则广告中的第二个动词形态就和前面的不对应，因此属于一种字形上的错误：
① If you intend to buy or sell your property or having any queries, please feel free to call me .
② You will be in charge of interviewing and shortlisting candidates and to assist in the recruitment of 500 staff.
在第一句里的“having”应改为“have”才对。不然，就要把这个分句完全写出来：
“…… or if you have any queries, ……”
第二句里的“and”是衔接前面的动名词“interviewing and shortlisting”和后面的动名词“assisting”。显然，这里不用动名词而用不定式动词“to assist”，也是犯了动词形式不对应的错误，非改正不可。
还有，根据字词的排列，“shortlisting”要排在“ interviewing”前面，才合逻辑。
①和②这类的错误相当普遍。虽然这样的错误不会影响人们对文章的理解，但是总不是件文字上的好事，还是多多注意，尽量避免好。
同样的，下列 5 个从学生作业中找出来的句子，也犯了同样的毛病：
③ This will enable the parent to experience the new style of life and allows him or her enough time to consider settling down.
④ Utopianism violates the human conscience, denies privacy to individuals and discard human rights.
⑤ They have to reach a decision on either sending their child to a day-care centre or employ a maid.
⑥ It is very hard to relate the stories through other means and at the same time retains the critical aspects of the book.
⑦ This problem can be solved by developing correct language skills, concentrating on studies day by day, and try not to exert too much pressure.
③到⑦句子里的动词形态的错误是明显的，改正也是容易的，即：
③ allow; ④ discards; ⑤ employing; ⑥ retain; ⑦ trying.