—How did you find your visit to the exhibition, John? 

—______

A．By taking a No. 3 bus.

B．Oh, wonderful, indeed.

C．I went there alone.

D．A classmate of mine showed me the way

清洁用的氢氧化物制品残留在铝制结构上对结构有什么影响（）

A、使材料变脆

B、使材料强化

C、腐蚀

D、氧化