―Are you still busy?

―Yes, I ________ my work, and it won’t take long.

A．just finish

B．am just finishing

C．have just finished

D．am just going to finish

铜片和锌片用导线连接后插入稀硫酸中，锌片为[ ]

A．阴极

B．正极

C．阳极

D．负极