Rock-climbing is a breathtaking activity, very popular nationwide among young people, ______ cooperation as well as courage plays an important role.
—When did you last hear __________ Jay? —He phoned me this morning, and we agreed __________ a time and place to meet.
The reason why he was late for school this morning is __________ his bike broke down on his way to school.
I didn't want to go with him, so I invented a (n) __________ about things I had to do on Friday.
"The final exam is coming. You'd better concentrate ___________ your study. " Mother informed me __________ it.
The shop was not far from here, so they went there on foot __________ by bus.