重写以下的文句子，并把用斜体显示的名词改为复数式。
D. Rewrite these sentences changing the nouns in italics into plural.
明确了复数附加成分的特征并统计其出现频率及相关句子。
Second, the passage made clear and definite the character of plural number appended element and count it's appearing frequency and related sentences.
但是，有时候不容易决定主词是单数还是复数。试选择适当的字，填妥以下的句子。
But sometimes it may not be easy to tell whether a subject is singular or plural. See if you can complete the following sentences by choosing the correct word.
应用推荐