香港保荐代表人已被要求同时最多只能接5宗订单

This pattern means to impose or establish a restriction, boundary, or rule on something. In formal news and policy language, 对 introduces the target, and 设下 introduces the limit or threshold being created.

This is a passive structure. 被 marks that the subject receives an action from another party. 已 adds the meaning of "already." Together, 已被要求 means "has already been required to."

不得 is a formal way to say "must not" or "may not," often used in rules and regulations. 超过 means "to exceed." Together, 不得超过 expresses an official upper limit.

This combination expresses a strict maximum. 同时 means "at the same time," 最多 means "at most," and 只能 means "can only." Together they emphasize that the number or action is limited to a maximum under the same time condition.

收紧 means "to tighten" or "to become stricter." 至 means "to" a specific level or amount. This pattern is common in formal and business Chinese to describe a rule, policy, or standard becoming stricter up to a stated number.