相 + Verb
相 (xiāng) means "mutually" or "each other" and is placed before a verb to indicate a reciprocal action. For example, 相对应 means "correspond to each other." It is more formal than 互相 and often appears in set phrases and written Chinese.
这两种语言的语法结构相似。
zhè liǎng zhǒng yǔyán de yǔfǎ jiégòu xiāngsì.
The grammatical structures of these two languages are similar.
朋友之间应该相互信任。
péngyou zhī jiān yīnggāi xiānghù xìnrèn.
Friends should trust each other.
这两个问题是相关联的。
zhè liǎng gè wèntí shì xiāngguān lián de.
These two issues are related to each other.