should

"His two-fingered gesture emphasized what he had told his boss to do with his job."

"The subjunctive mood is often used in formal writing to express a wish or a suggestion. "

"My obligation to my family means I need to visit them regularly. "

"The company recalled the toy car because it contained a known defective that could pose a safety hazard to children. "

"The sisters dressed similarly."

"The probability of passing the math test is high if you study regularly. "

"There is a possibility that the school will have a field trip next week. "

"It is of great importance that you act in a respectful manner towards the duke and duchess."

"The hospital volunteer group functions as an important auxiliary to the nursing staff. "

"What is your question?"

"Through sheer determination, we managed to escape from the tornado."

"A healthy diet is a beneficial for maintaining good health. "