— Kangkang, can you see a few people _____ Chinese kung fu over there?
— Oh, yes. They're cool!
A:are performing
B:perform
C:to perform
D:performing
36×78+36×18 =____
第二次工业革命是以____为核心的革命,它使人类社会从“____时代”过渡到“____时代”.