练习一
present;since;doctor;pollution;open;D;A;B;A;C;B;B;AD;B;wastaught;married;swim;came;havebeen;havelived;was.
练习二
changes;seen;infact;marry;southern;hadfun;won'tuntil;havebeenmarried;haskept;differentfrom
AADBDABB
练习三
possible;service;althgough;attraction;present;have;since;Howmany;Whenbuy;Havecarried;been;hasn't;sad;去掉but;yet;nextto;hasbeenopened;anylonger;howtoget;It'storead;Itiscame;butcame;haveknown;arefondof
练习四
CBACCB;notarrived;yet;Howlong;heard;Haseverbeen;Haschanged;yet;
IhavelivedheresinceIwasborn.
It'spleasanttoplayChinesechesswithmyclassmates.
AlthoughTomwasill,hewenttoschool.
WhereisMarry?Shehasgonetothecinema;
HaveyoubeentoBeijing?YesIhave.
Iusedtoplaycomputergames,nowIdon'tdoit.