Thank you, Derek, that makes some sense! But I think I need a certain noun to fill in a time report. For example:
11.00-11.30 A trip to customer's office.
11.30-14.00 An installation of wireless network.
In a formal report like that, I would probably write this:
11.00-11.30: travel to customer's office
11.30-14.00: installation of wireless network
Written communication in a business setting is usually very formal, but spoken English remains about the same as normal conversation.
By the way, you touched upon another question that I'm interested to know. What is the difference between the terms "client" and "customer"? Before getting the present job I was sure that a client is usually some firm that deals with another firm on a long-term basis, and seldom a man who buys something in a shop or a firm making a single purchase. It accords to Russian "клиент". On the contrary a customer is rather a man or a firm who buys something once, according to Russian "покупатель". But in our company our permanent client firms are usually called "customer". So I was a bit confused...
To add to what others have said, vocabulary for some of these concepts differs from company to company in anglophone countries. So in this case it would be more important to use what is the standard usage in your company than what seems more natural to a native English speaker.