32．Many experiments_____before the research team was able to get the exact data to carry on project.

A．have done

B．had been doing

C．had been done

D．have been done

下列哪项不是肿瘤的转移途径（）

A.远位转移

B.血道转移

C.接种转移

D.直接蔓延

E.淋巴道转移