flabbergast

"a plausible excuse"

"The dinghy was overwhelmed by the great wave."

"The sudden announcement of a school holiday caused bewilderment among the students. "

"My sister is very helpful, especially when it comes to organizing things. "

"The new schedule caused confusion among the students. "

"Everyone in the class needs to bring their textbook to the first lecture. "

"My sister's birthday is next week, and we're planning a party. "

"It was a surprise to find out I owed twice as much as I thought I did."

"The overwhelming pressure of deadlines made her feel stressed. "

"He made a ludicrous attempt to run for office."

"He was flabbergasted to find that his work had been done for him before he began."

"The students' high scores on the math test were confounded by the fact that they all had access to the answers beforehand. "