many times, my elderly mother still can’tremember how to light the gas

Excuse me, you are supposed to hand in your design now.–I’m sorry, my computer broke down, or I ________ it last night.

Reading books is very important for developing the students’ understanding of the world, _______?

Helen caught a cold the day before yesterday. But she’s ______ today.

Parents should pay attention to areas ______ their child is having difficulty and spend extra time helping him or her.