It is said that this project will take ________ two to three years, and cost about 200 million yuan.

It was difficult being in a foreign country, ________ if you don’t speak the language.

 He knows it's almost impossible to finish the ,task he but he wants to have a try ______.

Since production has risen ________, the personal income has increased year by year.

Though some foreign scientists had a ______ opinion of his new invention, his fellow workers never thought ____ of it.