单项选择题
A．dropped B．missed C．lost D．gone
A．finding excuses helps in learning B．to react negatively can be harmful C．hard-working is the key to success D．making use of the computer is important
A．People use the internet mainly to send emails. B．Computers are now more costly then ever before. C．Computers were costly and hard to use until the early 1990s. D．In the 1970s the Internet was easy to use but computers were costly.