a ture friend can see the pain in your eyes --- everyone else believes the smile on your facea\ whileb\ becausec\ befored\ until请说明理由好吗?

a ture friend can see the pain in your eyes --- everyone else believes the smile on your facea\ whileb\ becausec\ befored\ until请说明理由好吗?
a ture friend can see the pain in your eyes --- everyone else believes the smile on your face
a\ while
b\ because
c\ before
d\ until
请说明理由好吗?

a ture friend can see the pain in your eyes --- everyone else believes the smile on your facea\ whileb\ becausec\ befored\ until请说明理由好吗?
a)while是正确答案,而,然而的意思.——真正的朋友能从你的眼神中体察出你的痛苦,而其他任何人都相信你脸上的笑容.