下列句子划线部分的句子成分

题目

下列句子划线部分的句子成分
1.The problem (is how to feed a growing world population of almost 6 billion).
2.Alice made a promise （to allow Peter to take a pound of his flesh from whatever part of his body) if he-did not pay the money back at the end of three months.
3.At the time when Bassanio and Portia were getting married,a letter arrived from Antonio (saying that all his ships had been lost at sea and that he would have to give Shylock a pond of his flesh ).
4.what she was afraid of (was their taking her daughter abroad)
5.when I came out of the house he dropped the stick and explained that there was (something alive in our) rubbish bin
请简要说明

答案