To live on Mars, you need to wear boots which ________ to prevent you from floating off into space.
Jack usually goes to school by bike, ________ today he walked to school.
My English teacher ________ Mrs Lane now. She often helps me.
—________ did you start school? —I started school at five.
Robots ________ heavy work on farms in the future.
Lingling needs some vegetable. She ________ some in the market tomorrow.