Can words such as "preferably" be included in claims?
It seems that it is best not to use them
A certain patent book says that "preferably is" cannot appear in a claim. ..." statement, otherwise it will cause misunderstanding.
If a statement like "A, B or C is preferred" appears and is discovered by the examiner during the actual review stage, then you are lucky because the unclear defect can be overcome through modification. If you are granted authorization by luck, you can directly use Article 26 of the Patent Law to apply for invalidation of the claim on the grounds that the scope of protection is unclear. If it is an exclusive right, then the patent may be invalidated. If it is a subordinate right, , the situation is slightly better.