---I think English is ____unimportant subject.---I don’t think so. It is ____useful tool when we talk with foreigners.
He considered __________ the book, which was considered __________ a great help in his study.
The clothes in this shop are more beautiful than ____ of ______.
The meal mother cooked ______ very delicious.
It’s ____ difficult problem for the twins that ____ of them can work it out .
It was very cold the day before yesterday._______