什么叫热疲劳？
参考答案：
当金属部件被反复加热和冷却时，其内部就会产生交变热应力。在此交变热应力反复作用下，零部件遭到破坏的现象称为热疲劳。
设x1=1，x2=2均为y=alnx+bx2+3x的极值点，求a，b．
Which of the following statements regarding early termination of a forward contract is TRUE()
A. There is no way to terminate a forward contract early.
B. A party who enters into an offsetting contract to terminate has no risk.
C. Early termination through an offsetting transaction with the original counterparty eliminates default risk.
