题目

One winter, when I was eight, my father and I took a ride to Aunt Sally’s house. Halfway back home, the car _____ to shake and slow down. Dad ____ that the car had a flat tire. To make ____ worse, we were stuck in the middle of a snowstorm. I could hear the _____ in my dad’s voice as he said, “ we could only use a Christmas miracle right now.” I remember how much I ____ that old red car, mainly because the radio didn’t work. Actually, ____ really worked in that car, but ____, Dad got his miracle- the heater began to operate and we were very ____ that we wouldn’t freeze to death. We10．已知a=${∫}_{1}^{e}\frac{1}{x}$dx（其中e是自然对数的底数），z=$\frac{i}{a-i}$（其中i是虚数单位），则复数z的虚部为（　　）A．$\frac{1}{2}$B．-$\frac{1}{2}$iC．-$\frac{1}{2}$D．$\frac{1}{2}$i