????:1????????:????92?

2?????400?????

3????????

4?????vx

5????????????

????1???18???(??? ?)1???18???,???????2.7???????3.2???????????:????????2.7???????????????????????????3.2??1???????????????????2?????4.8?????????????4.6???,???,???,???

???????????,?,?????????

?????,???2.7???????????????????????;???????????????3.2??????????????????????????????????????????????(?)?????,??????????????????(?) ??:???