一も二も無く[ichimonimonaku] unhesitatingly
一言二言[hitokotofutakoto] a word or two
一石二鳥[issekinichou] killing two birds with one stone
一二に及ばず[ichininioyobazu] right away
一姫二太郎[ichihimenitarou] It's good to have a girl first and then a boy

うり二つ[urifutatsu] as alike as two melons (two peas in a pod)
黄道十二宮[koudoujuunikyuu] twelve signs of the zodiac
二度[futatabi] again
最小二乗法[saishounijouhou] least-squares method
三十二分音符[sanjuunibuonpu] 32nd note

其れ形[sorenari] in itself
悪形[akugata] villain's part
為替手形[kawasetegata] draft
異形[igyou] fantastic
井戸屋形[idoyakata] well roof

印形[ingyou] seal
雲形[kumogata] cloud formations
円錐形[ensuikei] cone
円筒形[entoukei] cylindrical
凹形[oukei] concavity