1 . After his parents passed away one by one, the little boy was left ________ (burden) with the responsibility of the whole family. (所给词的适当形式填空)

2 . _________(burden) with supporting the big family, he had to work hard to make ends meet. (所给词的适当形式填空)

3 . The university estimates that living expenses for international students is ________ burden for some of them. (用适当的词填空)

4 . We ________ with academic stress now.(burden)