He apologized to me ___ again.
When ______, the new railway will run for 250 miles.
It was really noisy in the workshop. Not until ______ at the top of my voice ______ to look at me.
______ the warning message, more visitors might have been trapped in the flood.
______ to sunlight for too much time will do harm to one’s skin.
It’s a difficult skill to master, but ______, it will benefit you for the rest of your life.