Jane’s pale face suggested that she ____ ill，and her parents suggested that she ____ a medical examination.

A．be；should have

B．was；have

C．should be；had

D．was；has

苔藓类植物可作为监测空气污染程度的指示植物是因为　[ ]

A．苔藓很容易吸收有害物质 　

B．叶只有一层细胞，对有毒气体敏感　　

C．一旦干燥便会死亡　 　　　

D．苔藓是低等植物