- it's so cold today!- ( ) yesterday.括号中为什么选so was it ,而不选so did it.

- it's so cold today!- ( ) yesterday.括号中为什么选so was it ,而不选so did it.
they think that () work hard is the key() success.
A/;of B.to,to
i often hear the old lady () in the next room.last night while i was reading in bed,i heard her () badly.
a.cough;coughing b.coughing;cough
they spent as many hours as they could () their lessons.
a.to study b.studying
Li Min studies English () the radio.
a.on b.by