Решить

To complete the task, we need to choose the appropriate grammar forms for the given words:

1. "He": This word refers to Robert and should start the second sentence.

2. "Task": This word fits in the phrase "He could do any kinds of ___." The correct usage is "tasks."

3. "Many": This word fits in the phrase "___ of us tried to make friends with him." The correct usage is "Many."

Here is how the completed sentences should look:

• "Robert was an outstanding student in our class because of his mathematical skills."
• "He could do any kinds of tasks."
• "Many of us tried to make friends with him but he spent."

Feel free to ask if you need further explanations!