e dropped_______ “s” in the word “acros”—Oh, ______letter “s” should be doubled like this“across”

Is there _______ underground station near here —Yes, there is.

He made a mistake, but then he corrected the situation _______ it got worse.

It was a great day ,____ we did not enjoy it at the beginning.

“We must keep in the library.” The woman said to me .