With a lot of difficult problems________, the newly－elected president is having a hard time.

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

Excuse me. Is the library open all day — . Only from 9 a.m to 4 p.m.

(2013·高考浙江卷)I ________ myself more－it was a perfect day.

Do you know how to use this word—-Sorry, but why not _______in the dictionary.