bit by bit

一点一点地，渐渐

biretta, Birmingham, birth, birth certificate, birth rate, birth-control, birthday, birthmark, birthplace, birthrate, birthright, biscuit, bisexual, bisexuality, bishop, bishopric, bismuth, bison, bistro, bit, bit part, bitch, bitchiness, bitchy, bite, biting, bitingly, bits, bitten, bitter, bitter-sweet, bitterly, bittern, bitterness, bitters, bittersweet, bitty, bitumen, bituminous, bivalve,