She thought ____ impossible to finish so much work in a day. [ ]

We are wondering ________ we canprevent people from polluting the earth.

You always spend only a little time on yourstudy. You really ____me down.— I’m sorry, Mum. I won’t do that again.

Last week, I bought an interesting story book, _____ is very beautiful.

We drove a long way to see him, only________that he had just left for the south.[ ]