巡道工在执勤时，以（）左右的速度全面查看线路。 A.1km/h B.2km/h C.

     Last Tuesday I took my two daughters, aged five and seven, to town by car. It began to rain _1_ so
I decided I would leave the children in the _2_ before I rushed into a shop. I warned the girls not to _3_ 
anything and told them I would be back within a few_4_. Then I locked all the doors and _5_ them
happily looking out of the window.
     I returned to the car in less than five minutes but the girls had   6_! I could hardly believe my _7_. The
car doors were _8_ locked, the windows tightly shut and in the back seat _9_ only two coats. Being
_10_, I ran to the corner of the street _11   there was no sign of them. I  _12_ up to an old lady nearby
and asked _13_ she had seen two small girls but she said "No"
     Feeling quite sick with _14_, I sat on the driver's seat, and tried to stop trembling. Suddenly, I _15  a
merry laugh behind me. I got out of the car, ran round to _16_ the boot  and there inside were two very
red-faced and excited _17  . They had obviously pulled out the back seat, _18   behind it and then been
unable to push the _19   forward again. With tears in my eyes, I leaned forward and _20_ their ears.