With so many people __in English every day, we can see it will be more and more important ___    a good knowledge of English．

A．to communicate, have

B．communicate; having

C．communicating; to have

D．communicated; to have

清蒸螃蟹是人们喜爱的一道美食，在蒸螃蟹时听到的“嗞嗞”声是通过______传播到我们的耳朵；蒸熟的螃蟹看起来是红色的，这是因为蟹壳______（填“反射”或“折射”）红光．人们能从不同的位置看见它，这是一种光的______现象，如将它拿到紫光照射的房间内，看到它是______色．