The road is covered with snow. I can’t understand ______ they insist on going by motorbike.
I have to go to work by taxi because my car _____ at the garage.
He is always helping people without expecting anything _____.
He speaks English well indeed, but of course not _____ a native speaker.
Computers have been made ______ clever that they can ______ problems like humans _______.
Old people need special care in winter, as they are very______ to sudden change of the weather.