Two explanations have been put forward for the intelligence problems.

Actually one explanation for these systems was put forward at the first Kepler conference.

However, several other explanations for its presence have been put forward.

A better explanation could have been devised and put in a brief sentence.

No explanation has been put forward for these articles presence here.

Two other possible explanations for the observed lag in the data have been put forward.

No scientific explanation for this contradiction was put forth at the time.

Various explanations have been put forward for why he encountered such a hostile reaction.

Several alternative explanations have been put forward for the crew's disappearance.

Various explanations have been put forward for these substrate features.