Why do climbers on Mount Everest carry bottles of oxygen? A. The weather is not cold. B. Climbing makes them tired. C. The air is very thin. D. They are thirsty.

She hasn't written to me for years.

=> It's years ____________________.

The beach is close to the hotel, so we can walk there.

=> We can go ______________________.

Thu often uses English to talk to Dave and Mary.

=> Thu often talks _____________________.

“Shall I help you with the exercises?” he said. 

=> He offered ___________________.