A: Do you think now is the right time to open the long position on crude oil futures?

B: I don’t think so. Weaker prospects for global growth could keep a lid on energy and commodity prices.

Note: This idiom can either mean “to keep the level of something from increasing drastically” or “to make sure that people do not do something or find out about something.” Some say it comes from cooking. When you cook certain food and don’t put a lid on it, it bubbles up from underneath and then bursts out of the pot, making a mess. You can keep a lid on certain information if it will embarrass your friend. People also say “put a lid on it” to mean “shut up.”