关于妊娠滋养细胞肿瘤，正确的说法是（）

A.侵蚀性葡萄胎可发生在流产后

B.绒毛膜癌可发生在葡萄胎之后

C.前次妊娠为异位妊娠，不发生绒毛膜癌

D.前次妊娠为足月产，不发生绒毛膜癌

E.绒毛膜癌最早出现的是脑转移

______ studies how sentences in spoken and written language form larger meaningful units such as paragraphs, conversations, and interviews.

A．Communicative Language Teaching

B．Meaning negotiation

C．Discourse analysis

D．Pragmatics