______ difficult it is, he is determined to ______ the experiment.

Which of these shirts do you like best?— I’ll take. They are all expensive and out of fashion.

You’ve dropped __________ “s” in the word “across”.－Oh, you are right, __________ letter “s” should be doubled like this “cross”.

The moon cakes _________ good. Could I have some more?

Mr Liu is a very popular doctor, so he is always busy______his work.[ ]