  Semi-quantum protocols construct connections between quantum users and
``classical'' users who can only perform certain ``classical'' operations. In
this paper, we present a new semi-quantum private comparison protocol based on
entangled states and single particles, which does not require pre-shared keys
between the ``classical'' users to guarantee the security of their private
data. By utilizing multi-particle entangled states and single particles, our
protocol can be easily extended to multi-party scenarios to meet the
requirements of multiple ``classical'' users who want to compare their private
data. The security analysis shows that the protocol can effectively prevent
attacks from outside eavesdroppers and adversarial participants. Besides, we
generalize the proposed protocol to other semi-quantum protocols such as
semi-quantum key agreement, semi-quantum summation, and semi-quantum anonymous
ranking protocols. We compare and discuss the proposed protocols with previous
similar protocols. The results show that our protocols satisfy the demands of
their respective counterparts separately. Therefore, our protocols have a wide
range of application scenarios.
