How long do you think ______ the computercompany brings out a new product

It isn’t like a duck to water to learn a foreign language , so you must study hard.

do da Vinci ______ a scientist, if he had not been so skilled in other areas.

Even scientists cannot completely ________for the strange behaviors of the animals before an earthquake. （原创）

What terrible news it was for her!She attempted to smile，but her voiceher．