Read the excerpt from the book "Language across the curriculum & CLIL in English as an additional language (EAL) Contexts", written by Angel M. Y. Lin (2016) How language varies has important educational implications. If language varies according to its use in different contexts, then students need to develop language proficiencies appropriate for use in different contexts. Regarding this, Cummins (1980/2001) has proposed two dimensions of language proficiency: Basic Interpersonal Communication Skills (BICS) and Cognitive Academic Language Proficiency (CALP).  We use BICS in our everyday life, such as in conversations with family members and friends, informal interactions with shop assistants when we go shopping or casual chit-chat on Facebook [and Instagram], WhatsApp, Twitter or Internet forums. In contrast, we use CALP to understand and discuss academic topics in the classroom and to read and write about these topics in school assignments and examinations. BICS are said to be used in contextembedded conversations and this means that the conversation is often face-to-face and offers many cues to the listener such as facial expressions, gestures and concrete objects of reference. CALP, on the other hand, is said to be necessary for context-reduced communication, such as those that take place in the classroom where there are supposed to be fewer nonverbal cues and the language is more abstract. However, in recent developments of new media interactions, this face-to-face context can often be a virtual one such as that of a [Google Meet] or WhatsApp conversation. It is, therefore, better to conceive of BICS and CALP not as discrete categories but as lying on a continuum. Similarly, it is best not to see spoken and written modes as discrete categories but as discrete categories but as lying on a ‘mode continuum’ (Lin, 2016, p. 9-10).   What is the function of the verb tense used in the phrase "Cummins (1980/2001) has proposed two dimensions of language proficiency"?