The actress often forgot her line but was very good at ad lib.
那个女演员常忘台词，却极擅长临时拼凑。
The speaker has to ad- lib his speech when his papers suddenly blow off the podium.
当演讲稿突然掉下台时，演讲者不得不现编词。
I had forgotten to bring my notes and had to speak ad lib.
我忘记带讲稿了, 只好临时讲几句.
