Which word completes the British expression for a close escape from danger, "a narrow ___"?

An epithalamium is a poem written for which occasion, like the one John Masefield wrote for November 20, 1947? An equation describing the behavior of quantum particles is named for which physicist, who lived from 1887 to 1961? An ermine is a type of which animal, especially in its white winter coat? An escalator is often referred to as a moving what? Which constructed language, introduced in 1887, has nouns that all end in "-o"? Many of Africa's Pygmy peoples, such as the Mbuti of the Ituri Forest, live in which country, once called the Belgian C… The largest share of people who applied for amnesty under the 1986 U.S. immigration reform lived in which state? What is it called when two couples go out together for an evening?