.—We haven’t heard from Jane for a long time?

—What do you suppose ________ her?

A．happened to

B．has become of

C．became to

D．was happened to

再热器汽温调节的常用的方法有：摆动式燃烧器、烟气再循环、分隔烟道挡板调节、喷水减温器（一般作为事故处理时用）。