water-tight and impene trable ❍ 他们搞小圈子，～。They formed a small coterie which was water-tight and impenetrable.
水泼不进，针插不进shui po bu jin,zhen cha bu jin
water-proof and impenetrable
水泼不进，针插不进
watertight and impenetrable ～的独立王国 independent kingdom that seals itself off from the outside—region or depart ment that refuses to obey the central authority