He kept yawning in class this morning. That is _____ he stayed up late doing his homework last night.

---Tell me something about your adventure in the rainforest, please.---We lost our way in the forest and ___ made matters worse was ___ night began to fall.

 I'd like to start my own business—that's ________ I'd do if I had the money.(2011·江西)

(2014·辽宁大连高三双基测试)—When choosing furniture，you only focus on function while I think more about the design.—That’s________we differ.

 —I prefer shutting myself in and listening to music all day on Sundays.— That’s _________ I don’t agree. You should have a more active life.