第30题: [单项选择]The heart is an important organ of circulation ______ function is to pump blood to all parts of the body. A. which B. whose C. of it D. its 参考答案:B 答案解析:本句的意思是:心脏是血液循环的器官,它的功能是把血液输送到身体的各个器官。选项A. which应该在定语从句中担任一定的成分,但空格之后的句子是主系表结构,主谓成分已经很齐全,所以不适合。选项C.of