—How______do you attend the evening classes?—______,three times per week.

Tonny’s parents thought he was at school, but ______ he was in an Internet bar.

Some people are bad at recalling names and faces, so it's possible that they have a condition called face blindness, ______ people suddenly have trouble recognizing family members, friends or even themselves．

 Mr. Green ______ goes to the park for a walk with some friends after supper.

Make sure the gas is turned off after cooking, which would        cause danger to our life.