I didn’t understand ______, so I raised my hand to ask.

He is having a family party in ________of his 84th birthday .

With the help of the smart phones, you ____ video chat with your friends on the phone.

It would seem to be a general truth__________ nothing is as straightforward as it at first seems

_____was the Nanjing-Changjiang Bridge open to traffic?——It was open to traffic in 1968.