[填空题]
The lowest pressure attailngvi-ospo wz8dtzo8ri( t6-19 4 p(rnashxs)v aq(e ,yaf5u5cdf7k ( (ble using the best available vacuum techniques is aboufh adac(5uk syf v(q) 5esx7,(t $10^{-12} N/m^2$ At such a pressure, how many molecules are there per $cm^3$ at 0$^{\circ} $C? $\frac{molecules}{cm^3}$