3.John stiffened his jaw so he wouldn't disgrace himself by crying.
约翰咬紧牙关,以免自己哭出来丢人现眼。
4.Threats merely stiffened his spine.
威胁只能他更加坚。
5.This paper presents an approximate analytic method for the stiffened torispherical shell with opening under uniform external pressure, that is, the equivalent spherical shell method.