— Linda is a hard – working dancer.

— Yes, when she was in the dancing school, she tried many times to pass her dance test, and __________ she succeeded.

A．by the end

B．at the end

C．in the end

D．on the end

密闭场地内使用含铅汽油的内燃机，会导致下列哪一种危害?

A.中铅毒 

B.中一氧化碳毒 

C.中二氧化碳毒