I. 根据句意及汉语提示写出句中所缺单词。 1. This ________(照相机) is now on sale for 19 dollars only 2. Are you going to America by boat or by ________(飞机)? 3. This tree is said to be one ________(千) years old 4. The boy often asks his teachers some ________(奇怪的) questions. 5. How long does it take to go to the airport by ________(出租车)?