She spends her money _________ books _________ on clothes.

Unfortunately, the research was limited __________ increasing economic profits, _________ protecting the environment.

Once you ______ the habit of smoking, it is hard to quit.

There fell a heavy snow last December, and this year ___ a good harvest.

At the meeting, the people were _____by the kindness and natural beauty of his mother     although there is a scar in her face.