不得不(bù dé bù)(1) 　“has no choice but to, has to, is obliged to do”　

HD. 1.443a(儒林外史); Shimura 1984 : 94 = 1995: 87(世説新語), Duan Yehui 2002 : 10, 35(論衡 etc.), YL 25(2002) : 263(史記, 漢書, 道行般若經);

Lk. 429a27. 須菩提當報恩。不得不報恩。(p)

AS. 17.21 = R. 34.9 = AAA. 135.8.nâkṛtajñaiḥ (“[We should] not be ungrateful.” [cf. AsP.tr.II 96 = AsP.tr. 15]); ZQ. 482b-10.終不敢違之; Zfn. 511c29.不得不報; not found at Kj. 540a23.; Xz(I). 769c27.如何不報; Xz(II). 870b16 = Xz(I) ; not found at Sh. 592b8.; Tib.Pk. 20b1 = D. 19b3f.bka’ drin mi gzo bar mi bgyi’o;