Theopeningceremonyisagreatoccasion.Itisessential_____forthat.

Of course，（）most immigrants did not get rich overnight ， but the of them were eventually able to improve upon their former standard of living.

Hewasluredintoacrimehewouldnot____________havecommitted.

Professor Johnson is said _____ some significant advance in his research in the past years.

Evenifhisletter（）tomorrow，it（）toolatetodoanything.