As soon as the sun had risen over the mountains, it became unbearable hot in the plain land. Identify the incorrect underlined word/phrase?

Explanation:
unbearably (adv.) হবে।
কারণ, linking verb এর পরে adverb বসে।
linking verb গুলো হচ্ছে to be, become, look, feel, smell, taste, seem, remain, appear, run, go, grow, read, turn ইত্যাদি।

Correct Sentence: As soon as the sun had risen over the mountains, it became unbearably hot in the plain land.