题目

Peter told us the work would be finished by next month, _____ personally I doubt very much.     A. that               B. when                C. which              D. it 答案：C18．过双曲线$\frac{{x}^{2}}{{a}^{2}}$-$\frac{{y}^{2}}{{b}^{2}}$=1（a＞0，b＞0）的一个焦点F作一条渐近线的垂线，垂足为点A，与另一条渐进线交于点B，若$\overrightarrow{FB}$=2$\overrightarrow{FA}$，则此双曲线的离心率为2．