【单选题】Text 【C1】______Space Agency is planning to【C2】______a spacecraft to the planet Mars. The spacecraft will be called Mars Observer. The project was to have【C3】______place in 1990. But it has been postpo...
【简答题】Fill in the blanks with the words given below. Change the form where necessary. Each word can be used only once. portable budget typical peer competitive complex sophisti...