I was about to walk over to Tom’ s seat when he________ and left.

not doing the things we like, but liking the things we have to do ______ makes life happy.

The Mekong River Commission has found no evidence the dams on the upper reaches have an influence on the water flow downstream.

Tom didn’t go hiking with his classmates ________his illness.

. It’s quite ____ of beginners to forget to use an article before a noun.