At 4, but I have to leave by 3:00 to get there on time.
四点,不过我三点必须离开,才能准时到那里。
You're way behind schedule.
你比预定的落后了。
For example, you might pick up a travel book and read a few pages before going to sleep. It is enough to dip into it and read bits here and there. In a word, this is tasting.