Whether the nation can emerge from poverty depends entirely on the people's will to work.(▼whether...の節が主語の場合,whetherはifで置き換えられない)
その事件に関連して記者達は首相に辞任する意思があるや否や尋ねた
Reporters asked the prime minister if [whether] he intended to resign over the affair.
2〔「…や否や」の形で,…するとすぐに〕
ホテルに着くや否や彼に電話した
I telephoned him as soon as I arrived at the hotel.
その青年は私の姿を見るや否や走り去った
No sooner had the young man caught sight of me than he ran away./The moment the young man caught sight of me he ran away./The young man had hardly [barely/scarcely] caught sight of me when [before] he ran away.