If a book is in French, ____ will be a challenge for me．

The rice made _____ possible to produce one-third more of the crop in the same field.

Half of ______surveyed in 16 countries say they go first to their closest friends to share their deepest wishes and darkest fears.

One should wash ___ hands before meals.

—What about today's temperature? —It's the same as, if the weather report is exact as usual, ________of yesterday．