Some people are sitting on the grass; others are walking along the lake .A. chatting and

问题补充：

Some people are sitting on the grass; others are walking along the lake, .

A. chatting and to laugh

B. to chat and to laugh

C. chatting and laughing

D. chatted and laughed

答案：

A. chatting and to laugh

B. to chat and to laugh

(答案→)C. chatting and laughing

D. chatted and laughed

解析：考查非谓语动词。句意：一些人坐在草地上，其他人在湖边散步，聊天，哈哈大笑。现在分词表示句子主语正在进行的伴随性动作，故选C。