1.pin down 确定；使受约束

We should use our secondary forces to pin down several enemy columns.
我们应该用助攻部队来牵制住敌人的几个纵队xXP1k_)DS+Ld。

And that is one problem with those who would wish to include measures of wellbeing in policymaking: it is hard to pin down what they wish to measure.
而这个错误恰恰是那些希望能在决策中加入对幸福的考量的政客常犯的：他们希望考量的那个东西，并无明确的定义i~ZyYtGz^U=yw7h。

2.date to 追溯到

We'll change the date to March 28th.
我们将把日期改到3月28日4~s1u@(^B,T!I]|P)r。

Yes you want the date to go perfectly but accept the reality that nothing on this earth is flawless.
是的，你希望约会很完美，但你也得接受现实：这个世界上没有一样东西是没有瑕疵的m|_+9_|G+oc((hFW;(T。