10. (8 points) January 1, 2015 was a Thursday, so what day of the week was June 1, 2015? 

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【Solution】Solution: Since $2015 \div 4=503 \cdots 3$, 2015 is a common year, and February has 28 days,
$$
\begin{aligned}
& (31 \times 3+30+28) \div 7 \\
= & 151 \div 7 \\
= & 21 \text { (weeks) } \cdots 4 \text { (days) }
\end{aligned}
$$

Since January 1, 2015 is a Thursday,
$$
4+4-7=1
$$

Therefore, June 1, 2015 is a Monday. The answer is: Monday.