Are bathroom signs on airplanes hard to understand?: A flight attendant on a US airline has written an article saying that passengers often don't understand that "vacant" means the bathroom is available for use, and "occupied" means that someone else is using it. Airlines and ships have in the past changed terms that they use with passengers. The phrase "mustering stations" has been replaced with "assembly point" because many people did not understand that the verb "muster" means to gather for instruction or inspection.

he has a screw loose

Peter: I was at a party last weekend, and Roy kept talking about his cats as if they were real people. Everyone thought he was very weird.

Bettina: I've heard him talk like that too. A lot of people have told me that he has a screw loose.

Explanation: When we want to say that someone has a mental problem, or is not behaving normally, we say "he has a screw loose." It is like saying that a machine has a part that is broken.

lack of focus

Mrs. Santiago: My daughter isn't doing well in school. The teachers say that lately she has a complete lack of focus.

Dr. Chen: We'll try to find out if this is a behavioral problem or a physiological problem. She might have an attention deficit disorder, or might have gone through some sort of recent trauma.

Explanation: We can use the phrase "lack of focus" to describe a number of symptoms related to dementia, attention deficiency, or other disorders that prevent a person from focusing and thinking clearly.

At cross-purposes

Dear Hui Zhong:

Our CEO told us to cut the budget, but our marketing director told us to increase our advertising and sales budget. These two requests are at cross-purposes. We need to have a meeting and sort this out.

Explanation: If there are two efforts moving in different and conflicting directions, we say they are "at cross purposes."