In the late 1970s, scientists detected “holes” in the ozone layer above the South and North Poles.

• Did scientists detect “holes” in the ozone layer above the South and North Poles in the late 1970s?
• When did  scientists detect “holes” in the ozone layer above the South and North Poles?
• Did  scientists detect “holes” in the ozone layer above the South and North Poles in the late 1970s or in the late 1980s?
• In the late 1970s, scientists detected “holes” in the ozone layer above the South and North Poles, didn't they?

At midnight, we were still driving through the desert.

• Were we still driving through the desert at midnight?
• When were we still driving through the desert?
• Were we still driving through the desert at midnight or at midday?
• At midnight, we were still driving through the desert, weren't we?