So you missed the lecture given by ProfessorSmith—- ____I got there 30 minutes before it finished

He is now _____, so he has to look for a job in a short timeOtherwise, his family will face the trouble oflacking money[ ]

Trees can stop the sand _____ towards the rich farmland in the south.

She usually keeps her valuables, such as jewels and money, ________ she believes secure

Now more and more people prefer __________ to _________ in order to reduce the air pollution.