A. Proper shops, even foreign, should be allowed in the Forbidden City.
B. The coffee shops do harm to the Forbidden City, so we should get rid of them.
C. Whether the shops are harmful depends on their country they are from.
D. The coffee shops in the Forbidden City used to be harmless, but not now.

A. Because people might have to migrate there someday.
B. Because it is very much like the earth.
C. Because it is easier to explore than other planets.
D. Because its atmosphere is different from that of the earth.