― Why ______ you stay in the countryside, where it is not convenient to go shopping?―But I’ve found it rather valuable for my health.

--- This must be a footprint of a tiger. --- It ____ be. A tiger’s should be much larger and deeper than this. 

 — Do you know where Mary is? I couldn’t find her anywhere. — Well . She        have gone far—her coat’s still here.

 Don't use water to put out the fire if oil catches fire. As is known, oil ________ float on water.

 The first snow of every year is always so exciting, but too much snow _________ cause trouble