单项选择题
Why did China suspend the imports of some products
单项选择题
单项选择题 Who is the man speaking to
单项选择题 A train traveling at a speed of 80 mph enters a tunnel that is 0.5 miles long. The length of the train is 0.25 miles. How long does it take for all of the train to pass through the tunnel, from the moment the front enters, to the moment the rear emerges