to have uncertainty regarding something
tener incertidumbre acerca de algo (tener incertidumbre acerca de algo)
"I have serious doubts about his honesty."
"Tengo serias dudas acerca de su honestidad." (tengo serias dudas acerca de su honestidad)
to give someone money to make them leave or stop working for...
to carefully examine reasons behind failure
to fail to happen or be completed
to continue for too long and become boring or tiring
to reduce tension after a disagreement
to stay confident and not let fear or doubt take over