Why was egypt of strategic importance in wwii?

To be frank, it wasn't. the british excuse for holding it was to distract the italians and keep the Mediterranean in the allies hands + shipping through it instead of around africa. 1. the italians only real objective was north africa, so no need to 'distract' them, they were already focused there. 2. the medditeranean was unimportant for shipping, it was far too dangerous with both german and italian submarines to get any more then 20-30% of supplys through, a complete waste. 3. some will say oil but at that time the production of oil in the area between egypt and syria was negligible, not nearly enough to sustain the troops in north africa much less the rest of germany. i don't know how much depth you want, PM me if you want to know more.
 

It turns into vapor and goes into the atmosphere