1). 破碎句

所谓破碎句，就是句子不完整，通常是没有谓语(或者说谓语是动词的非谓语形式，如分词)，或者是从句单独成句。

破碎句：She singing alone. (无谓语，singing是现在分词)托福成绩查询

正确句：She is singing alone.

破碎句：He did not come. Because he was sick. (从句单独成句)

正确句：He did not come because he was sick.

2).接连句

所谓接连据，就是两个句子直接连在一起，既未使用连词，也未使用正确的标点符号。

接连句: Professionals such as lawyers or accountants usually work longer hours than factory workers they have greater freedom in planning their time.

正确句一: Professionals such as lawyers or accountants usually work longer hours than factory workers. However, they have greater freedom in planning their time.

正确句二: Professionals such as lawyers or accountants usually work longer hours than factory workers; however, they have greater freedom in planning their time.

3).句子连接不正确

所谓句子连接不正确，就是两个独立的句子之间以逗号连接，这是不合英语语法的。正确的做法是以连词、分号、冒号、句号等连接两个句子。

不正确句: Breaking chalk into two pieces is a physical change, there is no change in the composition of the chalk.

正确句： Breaking chalk into two pieces is a physical change, so there is no change in the composition of the chalk.