In the past few years, so many areas throughout the world have been hit by such destructive earthquakes, snowstorms and tsunamis ________ we have never experienced before, ________ makes us worried a lot about nature disasters.

He didn’t tell me _______.

I want to improve my learning efficiency(效率) _____ have more spare time for my hobbies.[ ]

I don’t understand ______ such a silly question in class yesterday.

______name is Bob. _______is eleven years old（11岁）.