前后 1.(時(shí)間接近) around; about 春節(jié)前后 around the spring festival2.(自始至終) from start to finish; from beginning to end; altogether 這篇小說(shuō)從動(dòng)筆到定稿, 前后用了一年時(shí)間。 the novel took a year to write altogether, from start to finish. 他前后來(lái)過(guò)四五次。 he has been here four or five times altogether.3.(前面和后面) front and back 受到前后圍攻 be attacked both front and back; be caught between two fires; 房子前后都是果樹(shù)。 there are fruit trees in front and at the back of the house
Examination shows that the heart of andrias davidianus have three chamers - two atria and one ventride , the atria on the left of midline , the ventricle on the right of midline , and the atria are divided into two cavities by septum interatriale . there are four valvula semilunaris in conus arteriosus , but no spiral valve in conus arteriosus . the coronary artery is made by arterica carotis externa branches 研究結(jié)果表明,中國(guó)大鯢循環(huán)系統(tǒng)解剖學(xué)特點(diǎn)為: 1 .心臟:心房心室為左右排列,兩心房前后排列,共有4對(duì)動(dòng)脈弓,其中第二、三對(duì)動(dòng)脈弓匯合成一條背主動(dòng)脈;動(dòng)脈圓錐基部與心室相接處有4個(gè)瓣膜,動(dòng)脈圓錐內(nèi)沒(méi)有螺旋瓣,動(dòng)脈圓錐與腹側(cè)主動(dòng)脈干之間有3個(gè)半月瓣;房間隔有穿孔;冠狀動(dòng)脈由頸外動(dòng)脈的分支匯合而成。