When you approach a railroad crossing without flashing warning signals or crossing gates, you should:

you probably know the answer. stop asking stupid questions and making me waste my time. j.k. ; )   b.t.w. what are three ratios equivalent to 5 : 11? thx

permafrost layer, it exists beneath a layer of soil, rock or sediment.

answer; psychological influences;

answer; compulsions is a term that refers to repetitive behaviors performed;