Successful people always make________preparations for any potential setbacks. [ ]

most of the children in my time liked to play together under that big tree.___ during the summer holidays

I used to go to sleep ________ my bedroom light________.

（题文）Silk ______ one of the primary goods traded along the Silk Road by about 100 BC.

The two strangers have been talking in thepark for a long time as though they ______old friends.