What does the word flat mean in British English

A．He is a retired grocery store clerk.
B．He is the winner of the largest lottery jackpots in US history.
C．Instead of receiving the money in annual installments, he accepted a smaller payout, and was given a check for 42 million dollars.
D．He is not a high-tech investor.

A．A seven-day period free of violence would be the first test of the US brokered cease-tire between Israel and the Palestinians.
B．The countdown started last Wednesday.
C．There must be complete calm before moving on to the next phases.
D．The introduction of measures should take to rebuild trust.