Question

금요일에는 등산 갈 시간이 없어요 The comparison is frequently made with something implied and not explicitly stated. -은/는 can be used to mark the contrasted part to imply the existence (or absence) of other options. The -는데(요) verb ending can emphasize the sense of implication. It is important to use -은/는 carefully to avoid undesired or inappropriate implications.

Accepted Answer

I don't have time to go hiking this Friday. (implied: but I may have time another day)

Front	금요일에는 등산 갈 시간이 없어요
Back	I don't have time to go hiking this Friday. (implied: but I may have time another day)
Notes	The comparison is frequently made with something implied and not explicitly stated. -은/는 can be used to mark the contrasted part to imply the existence (or absence) of other options. The -는데(요) verb ending can emphasize the sense of implication. It is important to use -은/는 carefully to avoid undesired or inappropriate implications.

I Time 은/는 금요일에는 등산 갈 시간이 없어요